JP4881943B2 - Optical pickup device and information processing device - Google Patents

Description

  The present invention relates to an optical pickup device and an information processing apparatus including the optical pickup device. More specifically, the present invention relates to an optical pickup device and an information processing device that emit a short-wavelength semiconductor laser such as a blue-emitting semiconductor laser using a GaN-based semiconductor.

A digital versatile disc (DVD) is an information recording medium that can record digital data at a recording density about six times that of a compact disc (CD) and can write large-capacity digital data such as movies and music. Is known as a so-called optical disk.
In recent years, since the amount of information to be recorded has increased, an information recording medium having a larger capacity has been demanded.

  In order to increase the capacity of the information recording medium of the optical disc, it is necessary to increase the information recording density. This is generally realized by reducing the spot diameter of the laser beam emitted to the optical disc at the time of data writing and reading. In order to reduce the spot diameter of the light, the wavelength of the laser light can be shortened and the numerical aperture (NA) of the objective lens can be increased. In DVD, a light source with a wavelength of 660 nm and an objective lens with NA of 0.6 are used. Furthermore, for example, by using a blue laser beam having a wavelength of 405 nm and an objective lens having an NA of 0.85, information can be recorded at a recording density five times that of the current DVD.

  In addition to shortening the wavelength of laser light using a blue laser or the like, development of a technique for providing a plurality of recording layers on one optical disk has been advanced in order to further increase the recording density. For example, if it becomes possible to obtain an optical disc having two recording layers, the recording density has one recording layer in combination with the above-described shortening of the laser beam wavelength and the use of an objective lens having a large NA. About 10 times that of DVD.

  However, in an optical disk apparatus using a blue laser as a light source, the margin of optical power for reproduction in the blue laser is extremely small, so that quantum noise of the light source becomes a problem.

  For example, in a conventional optical disc apparatus disclosed in Japanese Patent Application Laid-Open No. 2000-195086, an optical pickup apparatus provided with an intensity filter that is a light beam transmission adjusting means that can be taken in and out substantially perpendicularly to a laser beam path is disclosed. In this optical disc apparatus, the intensity filter is inserted into the laser beam path during reproduction, and the intensity filter is moved away from the path of the emitted light during recording. Thereby, for example, the quantum noise of the semiconductor laser can be kept low, and high quality reproduction is possible.

  However, since this optical disc apparatus is provided with an intensity filter that can be taken in and out perpendicularly to the path of the laser beam, a space for moving the intensity filter is essential. As a result, there has been a problem that the optical pickup device is increased in size.

  In order to solve such a problem, another optical pickup device provided with an intensity filter that moves on the optical axis by rotation instead of the intensity filter that moves linearly on the optical axis is conceivable. Hereinafter, the optical pickup device will be described with reference to FIGS.

  FIG. 11 shows a configuration of a conventional optical pickup device. When the GaN-based semiconductor laser light source 41 emitting blue light emits a blue light beam, the light beam enters the light beam transmission adjusting means 200. The light beam transmission adjusting means 200 is rotated to a predetermined position depending on whether data is read from the optical disc 50 or data is written to the optical disc 50, and the position of the intensity filter is adjusted. The light beam that has passed through the light beam transmission adjusting unit 200 is reflected by the beam splitter 42, converted into parallel light by the collimator lens 43, reflected by the mirror 44, transmitted through the objective lens 45, and condensed on the optical disk 50. The

  At the time of reading data, the condensed light beam is reflected by the recording layer of the optical disc 50, reaches the beam splitter 42 through the reverse path, passes through the beam splitter 42, and enters the photodiode 48 through the multi lens 47. To do. The photodiode 48 is a so-called photodetector, and outputs an electrical signal based on the position and intensity of incident light. Data is reproduced based on the electrical signal.

  On the other hand, when writing data, a light spot is formed on the information layer by the condensed light beam. As a result, the state of the recording layer where the light spot is formed, for example, the crystal state changes according to the data to be written. As a result, data is written on the optical disc 50 as a change in the state of the recording layer.

  FIG. 12A is a perspective view when the light beam passes through the optical filter of the light beam transmission adjusting unit 200, and corresponds to the arrangement at the time of data reading. The light beam transmission adjusting unit 200 includes a transmission element 201. The transmissive element 201 has a first set of parallel planes composed of two parallel planes and a second set of parallel planes composed of two parallel planes. An optical filter 201a that attenuates the optical power of the transmitted light beam is applied to at least one plane of the first set of parallel planes. The light beam transmission adjusting unit 200 includes a support member 104 that supports the transmission element 201 and a rotation driving unit 105 that rotates the transmission element 201 around the rotation shaft 103. The support member 104 rotates the rotation shaft 103 so that the transmission element 201 can rotate around the rotation axis 103 parallel to the four planes constituting the first parallel plane set and the second parallel plane set of the transmission element 201. I support it. The rotation drive unit 105 drives the transmission element 201 to rotate about the rotation axis 103.

FIG. 12B is a perspective view when the light beam does not pass through the optical filter 201a of the light beam transmission adjusting unit 200, and corresponds to the arrangement at the time of data writing. The light beam transmission adjusting unit 200 switches the position where the light beam passes through the first set of parallel planes of the transmission element 201 and the position where the light beam passes through the set of second parallel planes by rotating around the rotation axis 103. Thus, it is possible to switch between the case where the light beam passes through the optical filter 201a and the case where it does not pass through. When the light beam passes through the optical filter 201a, the optical power can be suppressed lower than when the light beam does not pass.
JP 2000-195086 A

  However, the configuration in which the transmissive element 201 of the light beam transmission adjusting unit 200 is rotated enables the miniaturization, while improving the component accuracy and assembly accuracy of the light beam transmission adjusting unit 200, and at the time of mounting and operation. Another problem arises that the angular deviation in time must be reduced.

  More specifically, the transmissive element 201 is an integrated element having a transmissive surface having the optical filter 201a and a transmissive surface not having the optical filter 201a, and the light power is adjusted by switching the transmissive surface by rotation. Therefore, when the light beam passes through the transmission surface having the optical filter 201a, the transmission distance of the light beam is equal to the length L of the surface not having the optical filter 201a. On the other hand, when the light beam passes through the transmission surface that does not have the optical filter 201a, the transmission distance of the light beam is equal to the length L of the surface that has the optical filter 201a.

  When the surface of the transmissive element 201 is not perpendicular to the optical axis, that is, when an incident angle shift occurs, the light is refracted on the surface of the transmissive element 201. The optical axis shifts. FIG. 13A shows a state when there is no deviation of the incident angle of the light beam to the transmissive element 201 of the light beam transmission adjusting means 200. On the other hand, FIG. 13B shows a state of optical axis deviation when there is a deviation in the incident angle of the light beam to the transmissive element 201. According to FIG. 13A, the transmission distance of the light beam is equal to the length L of one side of the transmission surface. Therefore, as shown in FIG. 13B, when the incident angle deviation h of the light beam occurs, the transmission distance becomes longer in proportion to the length L of one side of the transmission surface, so that the optical axis deviation D occurs.

  It should be noted that the length L of one side of the transmission surface of the transmission element 201 must be a certain length or more in order to ensure a size necessary for reliably transmitting the light beam, that is, an effective diameter. That is, it can be said that the transmission distance depends on the length. As described above, when the transmission distance is increased, the optical axis deviation D after transmission caused by refraction when the incident angle deviation of the light beam occurs increases in proportion to the transmission distance, so that the accuracy of parts and assembly can be improved. Further, it is necessary to reduce the angle deviation.

  Further, as shown in FIG. 11, the light beam transmission adjusting means is disposed in a region where the light beam emitted from the semiconductor laser light source 41 is diffused. Even in such a situation, there is a condition that the transmission element must transmit the light beam without losing the light beam.

  An object of the present invention is to provide an optical pickup device that suppresses the deviation of the optical axis generated by the light beam transmission adjusting means for adjusting the optical power of the light beam emitted from the light source and does not obstruct the path of transmitted light, And providing an information processing apparatus.

The optical pickup device according to the first aspect of the present invention includes a light source that emits a light beam having a predetermined optical power,
A light beam transmission adjusting mechanism for adjusting the transmission amount of the light beam;
A condensing member that condenses the light beam transmitted through the light beam transmission adjusting mechanism on an information recording medium,
The light beam transmission adjusting mechanism is
A first transmissive element having a first transmittance;
A second transmissive element having a second transmittance higher than the first transmittance;
A support member that rotatably supports the first transmission element and the second transmission element around a rotation axis parallel to the first transmission element and the second transmission element;
A rotation drive unit that rotates the first transmission element and the second transmission element around the rotation axis;
By driving the rotation driving unit and switching between a first position where the light beam is transmitted through the first transmission element and a second position where the light beam is transmitted through the second transmission element, respectively, the predetermined optical power is used. In an optical pickup device that selectively outputs a light beam having a small first optical power and a light beam having a second optical power that is greater than the first optical power and less than or equal to the predetermined optical power,
When the light beam passes through one of the first transmissive element and the second transmissive element, the other of the first transmissive element and the second transmissive element is at an angle inclined with respect to the optical axis, The light beam transmitted through the transmissive element is disposed at an angle along the path in which the light beam diffuses.

  In addition, one of the first transmissive element and the second transmissive element through which the light beam is transmitted can be inclined with respect to the optical axis of the light beam.

  Further, the angle may be an adhesion prevention angle for preventing dust from adhering to the other transmissive element.

  The transmission distance when the light beam passes through the first transmission element is shorter than the length of each side constituting the surface of the second transmission element, and when the light beam passes through the second transmission element. The transmission distance may be shorter than the length of each side constituting the surface of the first transmission element.

  The transmission distance when the light beam passes through the first transmission element or the second transmission element may be shorter than the length of the side constituting the incident surface of any of the transmission elements.

  The light source may be a semiconductor laser that emits light in a wavelength region from green to ultraviolet.

  The light source may be a semiconductor laser that emits light in a blue wavelength region.

  An information processing apparatus according to a second aspect of the present invention is based on the optical pickup device according to the first aspect further including a photodetector that detects reflected light from the information recording medium, and the detected reflected light. And a signal processing circuit for generating at least one of a reproduction signal and a servo signal.

  The information processing apparatus can be loaded with a plurality of types of information recording media having different numbers of recording layers, and the amount of optical power corresponding to the number of recording layers can be set on the loaded information recording medium. A light beam is emitted to read and / or write data. When the information recording medium having one recording layer is loaded, the information processing apparatus switches to the first position by rotationally driving the rotation driving unit and switches the first recording layer to the first recording layer. When an information recording medium having a plurality of recording layers is radiated with a light beam having optical power, the rotational drive unit is rotated to switch to the second position, and 1 of the recording layers. A light beam having the second optical power may be emitted to one of the two.

  According to the optical pickup device of the first aspect and the information processing apparatus of the second aspect, the light beam transmission adjusting mechanism that switches the light power of the light beam by rotating the two transmission elements having different transmittances is provided. . Since the thickness of the transmission element of the light beam transmission adjustment mechanism is not limited by the effective diameter of the light beam, the light beam transmission adjustment mechanism causes a deviation in the incident angle of the light beam even if the component accuracy and assembly accuracy are the same as the conventional one. The deviation of the optical axis after transmission caused by refraction can be kept small. In addition, it is possible to improve device reliability and reduce manufacturing costs.

  Further, according to the optical pickup device, in addition to the above-described effect, when the light beam is transmitted through one of the first transmissive element and the second transmissive element, the other of the first transmissive element and the second transmissive element is Since the light beam is disposed at an angle inclined with respect to the optical axis, the other transmission element does not interfere with the path of the light beam that is transmitted through the transmission element and diffused.

An optical pickup device that is an embodiment of the present invention and an information processing device including the optical pickup device will be described below with reference to the drawings. In each figure, the same or similar components are denoted by the same reference numerals.
(First embodiment)
FIG. 1 shows a functional block configuration of an optical disc apparatus 10 which is an example of the information processing apparatus according to the present embodiment. The optical disc device 10 includes an optical pickup device 11, a signal processing circuit 12, and a servo control circuit 13. Although FIG. 1 shows the optical disk 14, this is for convenience of explanation and is not a component of the optical disk device 10.

  First, an outline of the operation of the optical disc apparatus 10 will be described. The optical pickup device 11 emits a light beam to the optical disc 14 to detect the reflected light from the optical disc 14 and outputs a light amount signal corresponding to the detection position and the detected light amount of the reflected light. The signal processing circuit 12 responds to a light amount signal output from the optical pickup device 11, a focus error (FE) signal indicating a focused state of the light beam on the optical disk 14, a focus position of the light beam, and a track of the optical disk 14. A tracking error (TE) signal or the like indicating the positional relationship is generated and output. The FE signal and the TE signal are collectively referred to as a servo signal. The servo control circuit 13 generates and outputs a drive signal based on these signals. The drive signal is input to an actuator coil 6 of the optical pickup device 11 described later, and the position of the objective lens 5 is adjusted. Thus, the focal point of the light beam emitted to the optical disc 14 is controlled so as not to deviate from the recording layer.

  In a state where the focal point of the light beam is controlled so as not to deviate from the recording layer, the signal processing circuit 12 outputs a reproduction signal based on the light amount signal. The reproduction signal indicates data written on the optical disk 14. Thereby, reading of data from the optical disk 14 is realized. Further, the optical pickup device 11 can write data on the optical disk 14 by making the optical power of the light beam larger than that during reproduction.

  Hereinafter, the configuration of the optical pickup device 11 will be described. One of the main features of the optical pickup device 11 according to the present embodiment is that the light beam transmission adjusting mechanism 100 is composed of two transmission elements having different light transmittances. The light beam transmission adjustment mechanism 100 can adjust the optical power of the light beam by switching these transmission elements by rotational driving.

  As shown in FIG. 1, the optical pickup device 11 includes a light source 1, a light beam transmission adjusting mechanism 100, a beam splitter 2, a collimator lens 3, a mirror 4, an objective lens 5, an actuator coil 6, A lens 7 and a photodiode 8 are provided.

  The light source 1 is a GaN-based semiconductor laser that emits blue light. The light source 1 also emits coherent light for reading and writing data to the recording layer of the optical disc 14.

  The light beam transmission adjusting mechanism 100 is an optical element that changes the light power by changing the light transmittance and keeping the quantum noise of the light beam emitted from the light source 1 low. Here, a detailed configuration of the light beam transmission adjusting mechanism 100 will be described with reference to FIGS. 2A and 2B.

  2A is a perspective view when the light beam 20 emitted from the light source 1 passes through the optical filter of the light beam transmission adjustment mechanism 100, and FIG. 2B shows the optical filter of the light beam transmission adjustment mechanism 100. It is a perspective view when not passing through. The light beam 20 travels in the direction indicated by the arrow.

  The light beam transmission adjustment mechanism 100 includes a first transmission element 101, a second transmission element 102, a rotation shaft 103, a support member 104, and a rotation drive unit 105. An optical filter 101a having a transmittance of 50% is applied to the first transmission element 101, and the optical filter 101a attenuates the optical power of the transmitted light beam 20. On the other hand, the optical filter 101 a is not applied to the second transmissive element 102, and the second transmissive element 102 transmits the light beam 20 while maintaining the optical power of the light beam 20. The support member 104 rotatably supports the first transmissive element 101 and the second transmissive element 102 in the direction around the rotation shaft 103. The rotation shaft 103 is parallel to the first transmissive element 101 and the second transmissive element 102. The rotation driving unit 105 rotationally drives the first transmissive element 101 and the second transmissive element 102 in the direction around the rotation axis 103.

  The light beam transmission adjusting mechanism 100 uses the rotation drive unit 105 to rotationally drive the rotation shaft 103 in the direction around the axis, so that the light beam 20 is transmitted through the first transmission element 101 as shown in FIG. 2A. Or it can switch whether it permeate | transmits the 2nd transmissive element 102 as shown to FIG. 2B. That is, it is possible to switch whether the light beam 20 passes through the optical filter 101a or not. The light power when the light beam 20 is transmitted through the optical filter 101a is 50% of the light power when it is not transmitted.

  Refer to FIG. 1 again. The beam splitter 2 separates the light beam emitted from the light source 1. The collimating lens 3 converts the light beam emitted from the light source 1 into parallel light. The mirror 4 reflects the incident light beam and directs the reflected light beam to the optical disk 14. The objective lens 5 focuses the light beam on the recording layer of the optical disk 14. The actuator coil 6 changes the position of the objective lens 6 in a direction perpendicular to the optical disc 14 or in a direction parallel to the optical disc 14 according to the level of the applied drive signal. The multi lens 7 focuses the light beam on the photodiode 8. The photodiode 8 receives the light beam reflected by the recording layer of the optical disk 14 and converts it into an electric signal (light amount signal) according to the light amount. Note that the photodiode 8 may include a plurality of light receiving elements. The signal processing circuit 12 that receives the light amount signal generates an FE signal and a TE signal using information on which light receiving element the light amount signal is output from.

  Next, an operation when the optical disc apparatus 10 reads and writes data will be described. As a premise, when the optical disk 14 has two recording layers, it is assumed that the transmittance of the layer near the objective lens 5 is set to about 50%. For this reason, the magnitude of the optical power required for recording / reproducing with respect to the optical disc having two recording layers is about twice that required for the optical disc having one recording layer. The optical pickup device 11 according to the present embodiment will be described as having a function of switching the magnitude of the optical power depending on whether the recording layer of the optical disc 14 is one layer or two layers.

  First, the light source 1 emits a light beam 20 having a predetermined optical power. At this time, it is assumed that the light beam transmission adjusting mechanism 100 is disposed so that the light beam passes through the optical filter 101a. The light beam emitted from the light beam transmission adjusting mechanism 100 is reflected by the beam splitter 2, converted into parallel light by the collimator lens 3, and reflected by the mirror 4. Thereafter, the objective lens 5 focuses the light beam on the recording layer of the optical disk 14. Reflected light from the recording layer passes through the optical pickup device 11 and enters the photodiode 8. The signal processing circuit 12 determines the number of recording layers of the optical disc 14 from the signal amplitude of the light quantity signal. Various other determination processes can be considered. For example, discriminating information for specifying the number of layers at the time of manufacture may be recorded on the inner periphery of the optical disc 14, and the discriminating information may be read as a reproduction signal to specify the number of layers. Alternatively, since the intensity of reflected light varies depending on the type of recording medium when the laser beam is irradiated, the intensity of the reflected light may be detected and determined by the signal processing circuit 12. Alternatively, when the optical disk 14 is loaded in a state of being stored in a cartridge, the determination may be made according to the shape of the cartridge, which differs depending on the type of the optical disk 14. Either can be detected using the optical and / or physical properties of the loaded optical disc.

  When it is determined that the optical disk 14 has one recording layer, the light beam transmission adjustment mechanism 100 rotates the first transmission element 101 and the second transmission element 102 so that the first transmission element 101 The position is set to a position perpendicular to the optical axis of the light beam 20 and the second transmission element 102 is out of the optical path. The optical filter 101a attenuates and transmits the light power of the incident light beam 20 to about 50%.

  On the other hand, when it is determined that the optical disc 14 has two recording layers, the light beam transmission adjustment mechanism 100 rotates the first transmission element 101 and the second transmission element 102 to perform the second transmission. The element 102 is set at a position perpendicular to the optical axis of the light beam 20 and the first transmission element 101 is out of the optical path. As a result, the second transmission element 102 transmits the optical power of the light beam without substantially attenuating.

  At the time of data writing, the state of the recording layer in the portion where the light spot is formed changes according to the content of the data. On the other hand, at the time of reading data, the light beam is reflected with a reflectance corresponding to the state of the recording layer of the optical disc 14. The light beam reflected by the recording layer is again transmitted through the objective lens 5, reflected by the mirror 4, transmitted through the collimator lens 3, transmitted through the multi-lens 7, and collected on the photodiode 8. As a result, the photodiode 8 generates and outputs a light amount signal. The signal processing circuit 12 generates a reproduction signal indicating the content of the written data, a focus error signal, a tracking error signal, and the like based on the light amount signal.

  According to the light beam transmission adjusting mechanism 100 according to the present embodiment, even when the optical axis of the light beam and the incident surface of the light beam transmission adjusting mechanism 100 are not perpendicular, that is, even when an incident angle shift occurs, the optical axis at the time of incidence. And the optical axis at the time of emission can be kept small. Hereinafter, the reason will be described with reference to FIGS. 3A and 3B.

  FIG. 3A shows a state when there is no deviation in the incident angle of the light beam 20 to the first transmission element 101 of the light beam transmission adjusting mechanism 100. The transmission distance when the light beam 20 passes through the first transmission element 101 is equal to the thickness T of the first transmission element 101. This distance is independent of the length L of one side of the transmission surface. On the other hand, FIG. 3B shows a state of optical axis deviation when there is an incident angle deviation h of the light beam 20 to the transmissive element 101. If the incident angle deviation h of the light beam 20 exists, an optical axis deviation d is generated in proportion to the thickness T of the transmissive element. The transmission distance of the light beam at this time is equal to or greater than the thickness T, but is sufficiently smaller than the length L of one side of the transmission surface.

  In the light beam transmission adjusting mechanism 100 according to the present embodiment, the transmissive element 101 and the transmissive element 102 having different transmittances are separate from each other. Therefore, the length L of one side of the transmissive surface of each of the transmissive elements 101 and 102, and the transmissive elements 101 and 102 can be set independently of the thickness T. That is, only the length L of the transmission surface is limited to the effective diameter of the light beam 20, and the thickness T of the transmission elements 101 and 102 can be reduced without being limited by the effective diameter of the light beam 20. This has the advantage that the deviation of the optical axis can be remarkably reduced as compared with the conventional light beam transmission adjusting means in which the transmissive element 101 and the transmissive element 102 are integrally formed.

  As described above, according to the optical disc apparatus 10 of the present embodiment, the light beam transmission adjustment mechanism can reduce the thickness of the transmission element, and therefore occurs due to refraction when the incident angle deviation of the light beam occurs. The deviation of the optical axis after transmission can be reduced. As a result, it is possible to improve device reliability and reduce manufacturing costs.

  In this embodiment, the optical power of the light beam 20 is switched by switching between the transmissive element 101 to which the optical filter 101a is applied and the transmissive element 102 to which the optical filter 101a is not applied. However, the light transmittance is different. The optical power of the light beam may be switched by switching two transmissive elements. Further, the number of transmissive elements that are different in light transmittance and can be switched is not limited to two, and may be three or more. Thereby, it is possible to switch to a multi-stage optical power according to the number of transmissive elements.

  In the present embodiment, the light beam is a semiconductor laser that emits blue light. However, it may be a semiconductor laser that emits light in the wavelength region from green to ultraviolet.

  In the present embodiment, the light beam transmission adjusting mechanism 100 switches the light power of the light beam 20 between the case where the information recording medium has one recording layer and the case where the information recording medium has two recording layers. In the case of an optical disc apparatus capable of writing and / or reading data on an information recording medium having multiple recording layers, the optical power of the light beam may be switched according to the number of recording layers of the optical disc. In the present embodiment, the light beam transmission adjusting mechanism 100 switches the light power of the light beam between the case where the information recording medium has one recording layer and the case where the information recording medium has two recording layers. However, the optical power of the light beam may be switched between reading data and writing data.

  Further, the collimating lens 3 and the objective lens 5 of the optical disc apparatus 10 are examples of condensing means or a condensing member. Further, the signal processing circuit 12 and the servo control circuit 13 of the optical disk device 10 can be realized as an optical disk controller separate from the optical pickup device 11 in the form of a single circuit or chip. Alternatively, the signal processing circuit 12 and the servo control circuit 13 may be provided in the optical pickup device 11. At that time, the signal processing circuit 12 and the servo control circuit 13 are components of the optical head.

  The optical disk 14 is an example of an information recording medium, and may be a card or the like that can optically read and write data.

(Second Embodiment)
Next, an optical pickup device of the second embodiment provided with a modified structure of the light beam transmission adjusting mechanism 100 in the above-described embodiment will be described below.
FIG. 4 shows an optical disk device 25 including the optical pickup device 26 of the second embodiment. The difference between the optical disk device 10 and the optical disk device 25 is that the optical beam transmission adjustment mechanism 100 provided in the optical pickup device 11 and the light beam transmission adjustment mechanism 110 provided in the optical pickup device 26 are different. However, the other components are not changed. Therefore, hereinafter, only the configuration of the light beam transmission adjusting mechanism 110 provided in the optical pickup device 26 of the second embodiment will be described. The difference between the light beam transmission adjustment mechanism 100 and the light beam transmission adjustment mechanism 110 is only that the angle formed by the two transmission elements is devised, and the other components are not changed.

  In the light beam transmission adjustment mechanism 100 in the first embodiment described above, as shown in FIGS. 2A, 2B, and 3A, the transmissive element 101 and the transmissive element 102 are arranged at an angle of 90 degrees orthogonal to each other. In addition, the light beam 20 is rotationally driven by the rotational driving unit 105 so that the light beam 20 is incident on the transmission surfaces of the transmission element 101 and the transmission element 102 perpendicularly. As shown in FIG. 1, the light beam transmission adjusting mechanism 100 is arranged until the light beam 20 emitted from the light source 1 travels while diffusing and enters the beam splitter 2. Therefore, the light beam 20 transmitted through one of the transmissive element 101 and the transmissive element 102 also travels to the beam splitter 2 while diffusing. Therefore, it is also conceivable that the non-transmission side transmission element through which the light beam 20 is not transmitted interferes with the light beam transmitted through the transmission element and diffused. For example, in the case shown in FIG. 2A, the light beam transmitted through the transmission element 101 on the transmission side is obstructed by the transmission element 102 on the non-transmission side. It is also conceivable that the end 102a obstructs the path of the light beam transmitted through the transmissive element 101.

  Therefore, in the light beam transmission adjustment mechanism 110 of the second embodiment, as shown in FIGS. 5A, 5B, 6A, and 6B, the transmission element 111 corresponding to the transmission element 101 and the transmission corresponding to the transmission element 102 are used. The transmissive element 111 and the transmissive element 112 are arranged such that the angle θ formed with the element 112 exceeds 90 degrees. Note that an optical filter 101 a having a transmittance of 50% is applied to the transmission surface of the transmission element 111 in the same manner as the transmission element 101.

  By arranging the transmissive element 111 and the transmissive element 112 in this manner, as is apparent from FIGS. 6A and 6B, the transmissive element on the light beam non-transmissive side, for example, the transmissive element 112 shown in FIG. The light beam is disposed at an angle that is inclined with respect to the optical axis and also in the horizontal direction, and follows the path of the light beam that is transmitted through and diffused through the transmission element on the light beam transmission side, such as the transmission element 111 shown in FIG. So as to be inclined. Therefore, it is possible to prevent the transmission element on the light beam non-transmission side from interfering with the path of the light beam that is transmitted and diffused.

  In addition, since the transmission element on the light beam non-transmission side is arranged to be inclined along the path of the light beam, the transmission path of the transmission element 111 and the transmission element 112 can be prevented. May be the minimum size required for the passage of the light beam. Therefore, the transmissive element 111 and the transmissive element 112 can be configured more compactly than the transmissive element 101 and the transmissive element 102 of the first embodiment. Therefore, it can also contribute to downsizing of the entire apparatus.

  Further, in the optical pickup device, an air flow is generated with the rotation of the optical disk 14, so that dust such as fibrous dust enters the optical pickup device. According to the second embodiment, with respect to such dust, as described above, the transmission element on the non-transmission side of the light beam is inclined along the path of the light beam, and is also inclined with respect to the horizontal direction. By arranging it, it is possible to slide off dust that is about to adhere to the transmission element on the light beam non-transmission side, and to prevent dust from adhering to and accumulation on the transmission element on the light beam non-transmission side. There is also. Therefore, the light beam radiated from the light source 1 can be always incident on the beam splitter 2 stably, contributing to the operational stability of the optical pickup device.

  As described above, the angle θ formed by the transmissive element 111 and the transmissive element 112 is set to an angle of inclination along the path of the light beam that is transmitted through and diffused through the transmissive element on the light beam transmission side, or an angle larger than that. be able to. In addition, based on the above-mentioned dustproof effect, the angle θ can be set to an adhesion prevention angle that can effectively prevent dust from adhering and accumulating on the transmission element on the light beam non-transmission side.

In the above description, the angle θ is an angle exceeding 90 degrees. However, when it is not necessary to consider that the light transmitting element on the light beam non-transmission side obstructs the path of the light beam, the angle θ can be set to 90 degrees as in the first embodiment. is there. Thus, by setting the angle θ to 90 degrees, the light beam transmission adjusting mechanism 110 can be configured more compactly compared to the case where the angle θ is set to an angle exceeding 90 degrees, and the transmission element 111 is also configured. There is an advantage that the arrangement and manufacture of the transmissive element 112 are easy.
However, in order to achieve the above-mentioned dustproof effect, the light transmitting element on the light beam non-transmitting side is arranged to be inclined. Due to the inclined arrangement, as shown in FIG. 7, the transmission element on the light beam transmission side, in FIG. 7, the transmission element 112 is inclined with respect to the optical axis of the light beam 20. Therefore, as described in the first embodiment, an optical axis shift occurs in the light beam transmitted through the transmissive element 112. However, even when the light beam 20 is transmitted through the transmission element 111 by being rotated by the rotation drive unit 105, the same optical axis deviation as that of the transmission element 112 occurs. Therefore, since the optical axis deviation amount is the same in the transmissive element 111 and the transmissive element 112, there is no problem as an optical pickup device.

  In each of the above-described embodiments, the angle θ between the transmission elements 101 and 111 provided in the light beam transmission adjustment mechanisms 100 and 110 and the transmission elements 102 and 112 is set to a right angle or an angle exceeding the right angle. It is not limited to the configuration of For example, like the light beam transmission adjusting mechanism 120 shown in FIG. 8, the transmissive element 101 and the transmissive element 102 may be arranged at an angle of less than 90 degrees. According to this configuration, the light beam transmission adjustment mechanism can be configured more compactly than when the transmissive element 101 and the transmissive element 102 are set to 90 degrees. However, since the light beam transmitted through one of the transmissive element 101 and the transmissive element 102 travels while diffusing, the other of the transmissive element 101 and the transmissive element 102 has a light beam that is diffused, particularly at the end thereof. It must be placed at an angle that does not interfere. As an example, the transmissive element 101 and the transmissive element 102 can be arranged at an angle of 85 degrees.

  Further, like the light beam transmission adjusting mechanism 130 shown in FIGS. 9 and 10, the transmissive element 101 or the transmissive element 102 through which the laser light emitted from the light source 1 is transmitted is inclined with respect to the optical axis 21 of the laser light. Are preferably arranged. In this way, by tilting the laser light incident surface of the transmissive element 101 or transmissive element 102 with respect to the optical axis 21 of the laser light, the reflected light emitted from the light source 1 and reflected by the transmissive element 101 or transmissive element 102 is again generated. It is possible to prevent the light from being incident on the light source 1 and to reduce the possibility that the generation of the laser light in the light source 1 will be hindered. According to the above arrangement, as described above, the optical axis shift occurs in the transmissive element 101 and the transmissive element 102. However, the optical axis shift amount is the same in both, and there is no problem as an optical pickup device. . 9 and 10 illustrate a case where the angle θ formed by the transmissive element 101 and the transmissive element 102 is less than 90 degrees. However, the present invention is not limited to this configuration, and the angle θ is set to 90 degrees or more. Even in this case, the reflected light is prevented from entering the light source 1 by inclining the laser light incident surface of the first transmissive element or the second transmissive element with respect to the optical axis 21 of the laser light. can do.

  According to the present invention, there is provided an optical pickup device that can suppress the deviation of the optical axis caused by the light beam transmission adjusting means to be small, and can realize improvement in device reliability, reduction in manufacturing cost, and the like, and such an optical pickup device. An information processing apparatus can be obtained.

It is a figure which shows the structure of the functional block of the optical disk apparatus provided with the optical pick-up apparatus in 1st Embodiment of this invention. FIG. 2 is a perspective view when the light beam passes through the optical filter of the light beam transmission adjusting mechanism in the optical pickup device shown in FIG. 1. FIG. 2 is a perspective view when the light beam does not pass through the optical filter of the light beam transmission adjusting mechanism in the optical pickup device shown in FIG. 1. In the optical pickup apparatus shown in FIG. 1, it is a figure which shows a state when there is no incident angle shift | offset | difference of the light beam to the 1st transmission element of a light beam permeation | transmission adjustment mechanism. In the optical pickup apparatus shown in FIG. 1, it is a figure which shows the state of a shift | offset | difference of an optical axis when the incident angle shift | offset | difference h of the light beam to the 1st transmission element of a light beam transmission adjustment mechanism exists. It is a figure which shows the structure of the functional block of the optical disk apparatus provided with the optical pick-up apparatus in 2nd Embodiment of this invention. FIG. 5 is a perspective view when the light beam passes through the optical filter of the light beam transmission adjusting mechanism in the optical pickup device shown in FIG. 4. FIG. 5 is a perspective view when the light beam does not pass through the optical filter of the light beam transmission adjusting mechanism in the optical pickup device shown in FIG. 4. FIG. 5 is a side view when the light beam passes through the optical filter of the light beam transmission adjusting mechanism in the optical pickup device shown in FIG. 4. FIG. 5 is a side view of the optical pickup device shown in FIG. 4 when the light beam does not pass through the optical filter of the light beam transmission adjusting mechanism. FIG. 5 is a diagram illustrating a case where the angle formed by the light transmitting element on the light beam transmitting side and the light transmitting element on the light beam non-transmitting side is set to 90 degrees in the optical pickup device illustrated in FIG. 4. It is a figure which shows the structure of the functional block of the optical disk apparatus provided with the modification of the optical pick-up apparatus shown in FIG. It is a figure which shows the structure of the functional block of the optical disk apparatus provided with another modification of the optical pick-up apparatus shown in FIG. FIG. 10 is an enlarged view of a transmission element on a light beam transmission side and a transmission element on a light beam non-transmission side in the optical pickup device illustrated in FIG. 9. It is a figure which shows the structure of the conventional optical pick-up apparatus. (A) is a perspective view when the light beam passes through the optical filter of the light beam transmission adjusting means, and (b) is a perspective view when the light beam does not pass through the optical filter of the light beam transmission adjusting means. is there. (A) is a figure which shows a state when there is no incident angle shift | offset | difference of the light beam to the transmission element of a light beam permeation | transmission adjustment means, (b) is a figure of the light beam to the transmission element of a light beam permeation | transmission adjustment means. It is a figure which shows the state of a shift | offset | difference of an optical axis when incident angle shift | offset | difference exists.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Light source, 2 ... Beam splitter, 3 ... Collimating lens, 4 ... Mirror,
5 ... Objective lens, 6 ... Actuator coil, 7 ... Multi lens,
8 ... Photodiode, 10 ... Optical disk device, 11 ... Optical pickup device,
12 ... Signal processing circuit, 13 ... Servo control circuit, 14 ... Optical disc,
100 ... Light beam transmission adjustment mechanism, 101 ... First transmission element,
101a ... Optical filter, 102 ... Second transmission element, 103 ... Rotating shaft,
104: support member, 105: rotational drive unit, 111: transmissive element, 112: transmissive element.

Claims (9)

A light source that emits a light beam having a predetermined optical power;
A light beam transmission adjusting mechanism for adjusting the transmission amount of the light beam;
A condensing member that condenses the light beam transmitted through the light beam transmission adjusting mechanism on an information recording medium,
The light beam transmission adjusting mechanism is
A first transmissive element having a first transmittance;
A second transmissive element having a second transmittance higher than the first transmittance;
A support member that rotatably supports the first transmission element and the second transmission element around a rotation axis parallel to the first transmission element and the second transmission element;
A rotation drive unit that rotates the first transmission element and the second transmission element around the rotation axis;
By driving the rotation driving unit and switching between a first position where the light beam is transmitted through the first transmission element and a second position where the light beam is transmitted through the second transmission element, respectively, the predetermined optical power is used. In an optical pickup device that selectively outputs a light beam having a small first optical power and a light beam having a second optical power that is greater than the first optical power and less than or equal to the predetermined optical power,
When the light beam passes through one of the first transmissive element and the second transmissive element, the other of the first transmissive element and the second transmissive element is at an angle inclined with respect to the optical axis, An optical pickup device arranged at an angle along a path in which a light beam transmitted through the transmissive element diffuses. The optical pickup device according to claim 1, wherein one of the first transmissive element and the second transmissive element through which the light beam is transmitted is inclined with respect to an optical axis of the light beam . The optical pickup device according to claim 1, wherein the angle is an adhesion preventing angle for preventing dust from adhering to the other transmissive element . The transmission distance when the light beam passes through the first transmission element is shorter than the length of each side constituting the surface of the second transmission element, and when the light beam passes through the second transmission element. 4. The optical pickup device according to claim 1, wherein a transmission distance is shorter than a length of each side constituting the surface of the first transmission element . 5. The transmission distance when the light beam passes through the first transmission element or the second transmission element is shorter than the length of the side constituting the incident surface of any of the transmission elements. An optical pickup device according to claim 1. The optical pickup device according to claim 1, wherein the light source is a semiconductor laser that emits light in a wavelength region from green to ultraviolet . The optical pickup device according to claim 1, wherein the light source is a semiconductor laser that emits light in a blue wavelength region . The optical pickup device according to claim 1, further comprising a photodetector for detecting reflected light from the information recording medium,
  An information processing apparatus comprising: a signal processing circuit that generates at least one of a reproduction signal and a servo signal based on the detected reflected light. A plurality of types of information recording media having different numbers of recording layers can be loaded, and a light beam having a light power corresponding to the number of the recording layers is emitted to the loaded information recording media. An information processing apparatus for reading and / or writing data,
  When an information recording medium having one recording layer is loaded, the rotation drive unit is driven to switch to the first position, and a light beam having the first optical power is applied to the recording layer. Radiate,
  When an information recording medium having a plurality of recording layers is loaded, the rotation driving unit is driven to switch to the second position, and the second optical power is provided to one of the recording layers. The information processing apparatus according to claim 8, which emits a light beam.

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